Perfume additives make consumer products such as home and body care products, and in particular laundry compositions, more aesthetically pleasing to the consumer and in many cases the perfume imparts a pleasant fragrance to fabrics treated therewith. The amount of perfume carryover from an aqueous laundry bath onto fabrics, however, is often marginal. By encapsulating perfume additives in microcapsules, the delivery efficiency and active lifetime of the perfume additives can be improved. Microcapsules provide several advantages, such as protecting the perfume from physical or chemical reactions with incompatible ingredients in the laundry composition, as well as protecting the perfume from volatilization or evaporation. Microcapsules can be particularly effective in the delivery and preservation of perfumes in that the perfumes can be delivered to and retained within the fabric by a microcapsule that only ruptures, and therefore releases the perfume, when the fabric is dry. The rupture of microcapsules can be induced by various factors such as temperature so that the contents are delivered when the capsule degrades. Alternatively the microcapsules can be compromised by physical forces, such as crushing, or other methods that compromise the integrity of the microcapsules. Additionally, the microcapsule contents may be delivered via diffusion through the capsule wall during a desired time interval.
Scent associated with laundered laundry is important to many consumers. There are many so called “touch points” that consumers associated with during the laundry experience. Non-limiting examples of these touch points include the freshness experience associated with opening a fabric care container, opening a washing machine after washing laundry, opening a laundry dryer after drying laundry, and freshness associated with wearing laundered clothes. It has been reported that there is a significant portion of consumers that will fold and put away their laundry about one day after having laundered laundry. Freshness while folding laundry about one day after having laundered laundry also signals to the consumer that the laundry is clean.
Multilayered capsules are known in the art. US 2005/0112152 generally describes encapsulated fragrance further coated with a second coating, such as a cationic coating. British patent application GB 1257178 discloses multicoated capsules produced by forming a secondary film layer at the interfaces of hydrophilic and hydrophobic liquids in the defective parts of the already formed primary film layer, e.g., crackles, capillary micropores or the like present therein, to fill up the defects.
British patent application GB 1141186 discloses dual walled capsules produced by first precoating droplets or solid particles of an internal phase in an aqueous vehicle through an interfacial reaction between two reactants, one of which is present in the aqueous vehicle, the other being present in or on the internal phase; and then providing another coating by coacervation.
U.S. Pat. No. 5,180,637 describes double-walled microcapsules wherein the primary wall is composed of an amino resin prepared by polycondensation reaction and the secondary wall is formed by coacervation of a polyion complex of the resin with polystyrenesulfonic acid or salt thereof, whereby liquid droplets are deposited on the primary wall. While those microcapsules are said to have improved resistance to heat and moisture, the structure of the shell consisting of superposed distinct layers is likely to delaminate and provide products which are still highly permeable.
Fan et al. reports preparing microcapsules with triallylamine-containing core surrounded by polyelectrolyte shell of controlled thickness via layer-by-layer assembly technology (“Preparation of oil core/multilayerpolyelectrolyte shell microcapsules by a coacervation method,” Materials Science Forum (2011), vol. 675-677 (Pt. 2, Adv. Mat. Science and Technology), p. 1109-1112).
Although multilayered capsules are generally known in the art, the quality of these capsules is far from satisfactory. Thus, there is a need in the industry for microcapsules with improved barrier and release properties for encapsulated materials such as perfumes. The present invention satisfies this and other needs of the industry.